add Hermes plugin for Ponytail with command support and documentation

docs/agent-portability.md

@@ -12,6 +12,7 @@ to load in a given agent.
 | Codex | `.codex-plugin/plugin.json`, `hooks/hooks.json`, `hooks/`, `skills/` | Plugin install with the same skills plus lifecycle hooks for activation and mode tracking. |
 | OpenCode | `.opencode/plugins/ponytail.mjs`, `.opencode/command/`, `hooks/`, `skills/` | Server plugin injects the ruleset each turn via `experimental.chat.system.transform` and persists `/ponytail` switches; reuses the shared instruction builder. |
 | pi | `pi-extension/`, `skills/`, `hooks/` | Package extension: injects the ruleset each turn through the shared instruction builder and registers the `/ponytail` commands. |
+| Hermes Agent | `plugin.yaml`, `__init__.py`, `skills/` | Native Hermes plugin: injects active mode through `pre_llm_call`, rewrites gateway `/ponytail-*` skill commands into agent prompts, registers `/ponytail` mode switching, and exposes bundled skills as `ponytail:<skill>`. |
 | Gemini CLI | `gemini-extension.json`, `AGENTS.md`, `commands/`, `skills/` | Extension manifest points `contextFileName` at `AGENTS.md` for always-on rules, and reuses the existing `commands/*.toml` and `skills/`, which Gemini CLI auto-discovers. |
 | Cursor | `.cursor/rules/ponytail.mdc` | Always-on project rule. |
 | Windsurf | `.windsurf/rules/ponytail.md` | Project rule. |